FRIDAY, Oct. 19 (HealthDay News) -- Women who do not get enough calcium in their diet are at greater risk for developing a hormone condition caused by overactive parathyroid glands that leads to weak bones and fractures, a new study found.

Increasing calcium intake could reduce women's risk for the condition, known as primary hyperparathyroidism (PHPT), Dr. Julie Paik and colleagues at Brigham and Women's Hospital in Boston reported in the Oct. 18 online edition of the BMJ.

For the study, the researchers followed more than 58,000 U.S. women aged 39 to 66 with no history of PHPT, who were involved in the large, long-running Nurses' Health Study. The participants were divided into five equal groups based on their dietary calcium intake. Information on the women's calcium intake was also collected every four years over the course of 22 years. During this time, the investigators identified 277 cases of PHPT.

After taking age, body mass index (a measurement based on height and weight) and ethnicity into account, the study revealed that women with the highest calcium intake had a 44 percent lower risk for PHPT than the women with the lowest calcium intake.

The researchers noted that women who took just 500 milligrams of supplemental calcium daily had a 59 percent lower risk for PHPT than women who did not take any calcium supplements.

"Increased calcium intake, including both dietary and supplemental calcium, is independently associated with a reduced risk of developing primary hyperparathyroidism in women," Paik's team concluded in the report.

Future research should examine other environmental or lifestyle risk factors that could play a role in the development of PHPT, the study authors pointed out in a journal news release.

In response to the findings, James Norman, chief of surgery at the Norman Parathyroid Center in Tampa, Fla., wrote in an accompanying editorial that the study "provides evidence to support physicians in confidently encouraging female patients to take calcium supplements."

PHPT affects one in 800 people during their lifetime, and is most common among postmenopausal women aged 50 to 60 years, Paik and colleagues noted in the news release.

While the study found an association between calcium intake and PHPT, it did not prove a cause-and-effect relationship.

More information

The U.S. National Institutes of Health Office of Dietary Supplements provides more information on calcium.